The power system infrastructure includes power lines, transformers and other devices for power generation, power transmission, and power distribution. A power source generates power, which is transmitted along high voltage (HV) power lines for long distances. Typical voltages found on HV transmission lines range from 100 kilovolts (kV) to in excess of 800 kV. The power is stepped down to medium voltage (MV) power at regional substation transformers. MV power lines carry power through neighborhoods and populated areas. Typical voltages found on MV power lines power range from about 1000 V to about 100 kV. The power is stepped down further to low voltage (LV) levels by distribution transformers. LV power lines typically carry power having voltages ranging from about 100 V to about 600 V to customer premises. A power distribution system may include a group of MV power lines, LV power lines, distribution transformers, and other power monitoring and control devices within a given region.
One parameter that may be measured at various locations within a power transmission and distribution system is the power factor. Power factor is the ratio of real power to apparent power, and may be measured for example for a given MV power line. Real power measures the ability of a network load to perform work in a particular time, and is associated with power consumption by a resistive load. Apparent power is the product of voltage and current, and may be equal to or greater than the real power due to a reactive load. In a purely resistive circuit, voltage and current waveforms are in phase with each other, changing polarity at the same instant in each cycle. In such a circuit the power factor is one (the real power and apparent power are the same).
In a circuit having a reactive load, such as a circuit having a capacitive or inductive load, there may be a time difference (a phase delay) between the current and voltage waveforms of the alternating current (AC) power. In particular, the capacitive and/or inductive loads (collectively “reactive loads”) alternately store and release energy and may alter the phase between current and voltage. In such a circuit the power factor may be less than one.
Power lines may carry more current than otherwise necessary to provide power to portions of a power distribution network having reactive loads. The additional current may result in additional real power losses caused by the losses of the power lines in conducting the additional current and also may require the generating facility to produce more power.
Generally, it is undesirable for portions of a power distribution network to have a power factor that is significantly less than one. Production of such excess power in such circumstances is inefficient and is inconsistent with policies of conserving energy and preserving environmental resources. Further, in order to distribute the increased apparent power, the utility may need to build additional infrastructure (e.g., power lines) to carry the additional current to deliver the desired real power. Further, consumer utility meters typically measure only real power and consumers are charged for real power consumption. However, the cost of delivering power determines power rates. Thus, power utility rates may increase to reflect the utility company's cost of delivering the higher apparent power. Accordingly, there is a need to regulate the power factor of a power distribution system to thereby enable the power distribution system to operate in a more efficient manner. These and other needs are addressed by various embodiments of the present invention.